After years of speculation about when it would finally happen, Microsoft is releasing a version of Office for Apple's iOS today. And it's free...sort of.

I got a brief peek at the Office suite app running on an iPhone this week, and we will be downloading the app from Apple's iTunes store as soon as it's available for a full review. But from my brief preview, it's clear that this may not be exactly what some Office users were waiting for. That's because of two very big caveats about Office for iOS: it requires a subscription license of Office through Office 365, and it's optimized specifically for iPhone (sorry, iPad). The iWork team at Apple can breathe a collective sigh of relief.

But if you've already bought into Microsoft's vision for Office in the cloud and have subscriptions to Office 365 Home Premium, ProPlus, or an Office 365 Enterprise license that includes the Office desktop suite, then the new iPhone app is still a big bonus. It doesn't take up one of the 5 device license slots that a full copy on a PC does, and it provides most of the functionality of Office Mobile apps on Windows Phone 8.

Office Mobile is tied into the SkyDrive associated with a user's Office 365 credentials, so it's automatically in sync with content in the cloud. It also automatically associates with Office document files on iOS devices, so users can open and edit file attachments from Mail and save them back to the cloud or mail them back. Office Mobile allows you to create new documents or open existing ones, either by browsing folders in SkyDrive or by finding them through a recent files list (which synchronizes with your recent files from desktop applications).

At first blush, Office Mobile seems to be a good first step into iOS for Office. There's clearly been some hedging by Microsoft on the capability of the mobile app, however. The lack of an iPad-optimized version will peeve some users, obviously (you can't exactly run a presentation on an iPad in iPhone resolution, for example, which may keep Apple Keynote sales up). But creating a full-resolution Office Mobile app for iPad would probably cause problems for Microsoft's efforts to sell the Surface RT.

There's no word yet on an Office Mobile for Android. But it's a safe bet that Microsoft is at least preparing for that option.

After you install Office Mobile, you'll get a similar, mobile-friendly version of the install introduction from the full Office 2013.

After you install Office Mobile, you'll get a similar, mobile-friendly version of the install introduction from the full Office 2013.

Once it's got all the introductions out of the way, Office Mobile prompts you for your existing Office 365 credentials, or politely directs you to a page where you can buy a license.

You get the rights to 5 mobile devices with a Home Premium subscription (not counting Windows Phone, which comes with the Office Mobile app installed), in addition to the full client on 5 PCs and Macs. Mac users get Office 2011 for Mac OS X.

If you purchase an Office subscription plan in-app, you'll need to create a Microsoft ID.

Once you've got the whole Office subscription thing out of the way, sign in with your credentials and you're on your way.

The "Recent" navigation view gives a time-based view of the files you've touched in Office. You can also go hunting through your SkyDrive folders.

Big on readability, Word has viewer and editor modes for documents, so you can just navigate through to review or...

...you can get in there and change the content. I recommend light edits on the phone. You could run this on the iPad in blown-up view if you're keen on preserving your eyesight.

You can edit cells in spreadsheets, and even add charts.

Here's the slide sorter view in PowerPoint. PowerPoint is more powerful than you'd think on the iPhone. You can edit speaker notes and text in files; there's even a presentation rehearsal mode that you can run the app on in portrait orientation—the slide is shown on top, and the notes below.

Pass. Already have iWork and it's fine for what I do on phone and tablet.

If my Mac Office Pro 2011 dual license can't qualify me for even a trial, $@%& MS, why would anyone subscribe to Office 365 just to get this?

MS is either not very serious about iOS users or losing their mind. Office becomes ever less relevant, Excel is the only compelling app any more and who does heavy data work on a mobile?

They'd subscribe because Office is the standard office suite found in most businesses. It makes things easier when YOU are using the same application to generate reports, proposals, and so on as your coworkers and clients.

Oh great. Now MS is justifying the senseless need for our execs to get iEverything.

Edit: I'm not hating on Apple. I'm hating on the type of mind that refers to the Surface Pro as "Microsoft's iPad" and then wants to roll actual iPads out to everyone and their brother even though we don't have any business applications that will run on them and a two-man IT crew that has no time to implement any.

1) Does it support Word's change-tracking features?2) In-line equations? Do they work? Don't necessarily care about editing them, but are existing equations in a document rendered reasonably accurately?

Too bad about the lack of an iPad version; honestly, that's much more interesting to me.

No iPad support which is arguably the largest use case scenario.You have to subscribe to Office 365.You can't just buy it in the app store.

I honestly can't come up with a way they could have fucked this up any more. I guess they really didn't want to pay 1/3 of their sales to Apple. Of coure 100% of what they'll make now will pale in comparison to 2/3 of what they could have made if they'd done it right.

No iPad support which is arguably the largest use case scenario.You have to subscribe to Office 365.You can't just buy it in the app store.

I honestly can't come up with a way they could have fucked this up any more. I guess they really didn't want to pay 1/3 of their sales to Apple. Of coure 100% of what they'll make now will pale in comparison to 2/3 of what they could have made if they'd done it right.

Actually MS will not get 100% of the subs from the in app purchase. MS is giving Apple a cut of all NEW subs obtained through the app just like all devs that offer in app purchases.

I have to agree on no iPad support being a miss... but not surprised it only works with Office365... O365 is clearly the strategic direction for Microsoft, I am sure they would like to get rid of the licensed versions and go all subscription... as soon as they get enough customers on O365 they will drop the other licensing... Gartner wrote a paper saying Microsoft is offering companies sweetheart deals on O365 (undercutting Google Apps) trying to build adoption.

Embrace, Extend, Extinguish. I'd be more worried about iCloud becoming less useful with the addition of SkyDrive integrated into Office. The more Microsoft can push SkyDrive everywhere, the less useful Apple's specialized, only-in-our-ecosystem, competing products look like inferior products.

Other than iPhone backup and iTunes music/video/picture sync, why use iCloud when SkyDrive can be used at work, home, on Android, Windows Phone and your iDevices? When does Apple's walled garden approach begin to backfire? Is Microsoft really being the more, dare I say most, open platform from a closed source vendor these days?

Add Skype to the mix and doesn't Facetime take a hit when the Xbox One is released with native support? How does Facetime persist in the face of an iDevice integrated experience that works with millions of Xbox One's, hundreds of millions of PCs, Windows Phone, Android and iDevices?

Embrace, Extend, Extinguish. I'd be more worried about iCloud becoming less useful with the addition of SkyDrive integrated into Office. The more Microsoft can push SkyDrive everywhere, the less useful Apple's specialized, only-in-our-ecosystem, competing products look like inferior products.

Oh great. Now MS is justifying the senseless need for our execs to get iEverything.

Edit: I'm not hating on Apple. I'm hating on the type of mind that refers to the Surface Pro as "Microsoft's iPad" and then wants to roll actual iPads out to everyone and their brother even though we don't have any business applications that will run on them and a two-man IT crew that has no time to implement any.

I understand your problems reigning in executive expectations. However, the Surface RT is microsofts iPad (even if it is largely unsuccessful) and you would have the same challenges deploying them in the field. Maybe more since Apple has a well refined set of enterprise deployment tools and I don't believe any of the MS tools support the RT.

Why do I ignore the Pro? Because users are primarily using the pro as an ultra book. I doubt your executives would consider it as an ipad alternative.

Can't believe all the comments who are surprised that this app has such limitations.

They have released an app which does the absolute minimum so they can say "we have Office on iOS" while still retaining that Windows (Phone / Tablet / PC) is still the best place to get work done so they haven't killed off sales of their own products

Embrace, Extend, Extinguish. I'd be more worried about iCloud becoming less useful with the addition of SkyDrive integrated into Office. The more Microsoft can push SkyDrive everywhere, the less useful Apple's specialized, only-in-our-ecosystem, competing products look like inferior products.

Other than iPhone backup and iTunes music/video/picture sync, why use iCloud when SkyDrive can be used at work, home, on Android, Windows Phone and your iDevices? When does Apple's walled garden approach begin to backfire? Is Microsoft really being the more, dare I say most, open platform from a closed source vendor these days?

Add Skype to the mix and doesn't Facetime take a hit when the Xbox One is released with native support? How does Facetime persist in the face of an iDevice integrated experience that works with millions of Xbox One's, hundreds of millions of PCs, Windows Phone, Android and iDevices?

If MS can make Skype work out of the box with my phone number and no other configuration, I think you will be on to something.

Sean Gallagher / Sean is Ars Technica's IT Editor. A former Navy officer, systems administrator, and network systems integrator with 20 years of IT journalism experience, he lives and works in Baltimore, Maryland.